swi-prolog build crashed during documentation build

[matko]

I just ran a rebuild of swi-prolog for the Nix packaging and ran into the crash below. A rebuild right afterwards with no changes succeeded, so I suspect there's might be a weird race condition.

The crash seems to happen in retract.

This is for SWI-Prolog 9.2.6. Since I can't really reproduce this, I have no idea if this would still be an issue for the latest devel. For all I know this could be a case of a gamma ray hitting the wrong memory. I'm reporting this just in case.

build log fragment:

[2450/2735] -- CHR bootstrap compilation step 2
[2451/2735] Generating rdf2pl.html
FAILED: packages/RDF/rdf2pl.html /build/source/build/packages/RDF/rdf2pl.html 
cd /build/source/build/packages/RDF && /build/source/build/src/swipl -f none --no-packs /build/source/build/home/library/ext/ltx2htm/latex2html.pl -- --quiet rdf2pl && /nix/store/sa1yjb7xxrzcbd1bysj3r561vidfxxvb-cmake-3.29.6/bin/cmake -E remove /build/source/build/home/doc/manindex.db

SWI-Prolog [thread 1 (main) at Tue Aug 27 14:44:07 2024]: received fatal signal 11 (segv)
C-stack trace labeled "crash":
  [0] save_backtrace() at /build/source/src/os/pl-cstack.c:337 [0x7ffff7cfe850]
  [1] print_c_backtrace() at /build/source/src/os/pl-cstack.c:911 [0x7ffff7cfe919]
  [2] sigCrashHandler() at /build/source/src/os/pl-cstack.c:949 [0x7ffff7cfea2e]
  [3] __restore_rt() at ??:? [0x7ffff7a7e5c0]
  [4] visibleClause___LD() at /build/source/src/pl-inline.h:632 [0x7ffff7d32fdb]
  [5] firstClause___LD() at /build/source/src/pl-index.c:585 [0x7ffff7d327f9]
  [6] pl_retract1_va() at /build/source/src/pl-proc.c:3181 [0x7ffff7d236e4]
  [7] PL_next_solution___LD() at /build/source/src/pl-vmi.c:4811 [0x7ffff7d08802]
  [8] query_loop() at /build/source/src/pl-pro.c:147 [0x7ffff7d49a42]
  [9] prologToplevel() at /build/source/src/pl-pro.c:574 [0x7ffff7d498dd]
  [10] /build/source/build/src/swipl(+0x10a6) [0x4010a6]
  [11] __libc_start_call_main() at ??:? [0x7ffff7a6814e]
  [12] __libc_start_main_alias_2() at ??:? [0x7ffff7a68209]
  [13] /build/source/build/src/swipl(+0x10f5) [0x4010f5]
Prolog stack:
  [386] system:retract/1 [PC=1 in supervisor]
  [385] tex:write_html/1 [PC=5 in clause 7]
  [384] tex:write_html/1 [PC=8 in clause 3]
  [13] tex:run_latex2html/1 [PC=110 in clause 1]
  [12] tex:latex2html/2 [PC=57 in clause 1]
  [10] system:catch/3 [PC=2 in clause 1]
  [9] system:catch_with_backtrace/3 [PC=6 in clause 1]
  [8] prolog_main:main/0 [PC=31 in clause 2]
  [7] system:catch/3 [PC=2 in clause 1]
  [6] system:catch_with_backtrace/3 [PC=6 in clause 1]
  [5] $toplevel:run_init_goal/2 [PC=17 in clause 1]
  [2] system:catch/3 [PC=2 in clause 1]
  [1] $toplevel:$initialise/0 [PC=12 in clause 1]
  [0] system:$c_call_prolog/0 [PC=0 in top query clause]
Running on_halt hooks with status 139
Killing 16876 with default signal handlers
Segmentation fault (core dumped)

[JanWielemaker]

Good to know. Not seen this. Just for the record, this is on x86_64 hardware?

[matko]

Yes, x86_64.